Why Exercise Helps with Depression in Older People

One of exercise's great appeals to many people is that it can temporarily boost mood. According to new research, repeating this temporary boost on a regular basis might help older people lessen or avoid depressive symptoms.

By some estimates, as many as 20 percent of older Americans report some level of depression, compared to about 10 percent for the overall population. Research published in 2012 showed that, during an hour-long workout, the brains of older men (age 54-70) experienced an increase in their levels of tryptophan. This is considered significant because an increase in tryptophan is typically paralleled by an increase in serotonin activity; serotonin is a neurotransmitter associated with elevated mood. It's generally thought that one aspect of aging--and therefore one contributor to depressive symptoms in older people--is impairment in the brain's ability to transmit serotonin.

The new research, published in Applied Physiology, Nutrition and Metabolism, looked at what happens to serotonin levels when older people become regular exercisers. Sixteen men, with an average age of 64, did a one-hour workout at a moderate intensity level (about 70 percent of VO2 max, a conversational pace in running terms). As with the subjects in the 2012 study, their tryptophan levels were elevated after the workout.

The men then became regular aerobic exercisers. After 16 weeks of training, they repeated the one-hour workout. Again, the workout triggered an increase in tryptophan levels. In other words, becoming accustomed to exercise didn't significantly decrease the one-shot mood boost they got from working out.

"The data support the contention that repeated elevations in brain serotonin activity might be involved in the antidepressant effect of exercise training in older adults," the researchers concluded.

Scott DouglasScott is a veteran running, fitness, and health journalist who has held senior editorial positions at Runner’s World and Running Times.

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